/Engine/Source/Runtime/GameplayTags/Classes/GameplayTagsManager.h
Gets a Tag Container containing all of the tags in the hierarchy that are children of this tag, and were explicitly added to the dictionary
[FGameplayTagContainer](API\Runtime\GameplayTags\FGameplayTagContainer) RequestGameplayTagChildrenInDictionary ( const [FGameplayTag](API\Runtime\GameplayTags\FGameplayTag) & GameplayTag ) const